The present invention is directed to a new and improved cutting unit which is adapted to operate in line with a printing unit to cut and/or crease material printed in the printing unit.
Typically, cutting units have been used in line with printing units. The printing units normally print a plurality of carton blank printed images in a printed array. The cutting unit normally includes cutting cylinders which define a nip therebetween which receives the printed material from the printing unit. The cutting cylinders carry suitable cutting dies for purposes for cutting the printed image of the carton blanks from the material. Further, some provision is made for the removal of broke from the carton blanks.
Cutting dies which have been utilized with cutting equipment of the above-noted type have included die plates such as shown in U.S. Pat. No. 3,485,146 and U.S. Pat. No. 3,142,233. These patents disclose cutting and scoring dies which are formed of thin metal sheet material having lands formed thereon. The die plates may be formed in a variety of different ways and such will not be described herein. The die plates are relatively flexible and can be bent in an arcuate configuration and secured on cutting cylinders, which define a nip therebetween. The cooperating die plates include cutting lands which are formed substantially in a mirror image on the cooperating die plates. the cutting lands are spaced radially apart at the cutting nip so that the cutting lands never touch during the cutting operation. Typically, the cutting lands are formed so that there is a small amount of overlap of the cutting lands on the respective arbors at the cutting nip. The type of cut which is performed by such cutting lands has been termed a rupture cut.
The provision of a suitable apparatus for effectively utilizing the rupture cut principle has had a substantial amount of attention. Many patents disclose machinery relating to the use of such dies, for example, U.S. Pat. Nos. 3,375,762; 3,379,351; 3,578,761 and 3,435,737. Also, many patents relate to methods of making such dies, for example, U.S. Pat. Nos. 3,580,676 and 3,895,947.
The problems of adjustment in known apparatus has been acute since the die plates must be properly adjusted relative to each other and the printed image for purposes of effecting the cut. Also, the fact that the die plates are formed in the flat and then bent to extend through a substantial arc around a cylinder has created problems and inaccuracies. Further, the die plates have been made through the use of a step and repeat machine which also introduces inaccuracies when the die plates are relatively large.
In accordance with the present invention, an improved rotary cutting and creasing apparatus is provided which is capable of ready adjustment depending upon print length size of the image and which utilizes the rupture cut principle. In accordance with the present invention, a plurality of cylinder segments are secured to arbors which extend parallel to each other. The segments extend longitudinally of the arbor and extend around a portion of the circumference of the arbor. Each segment is provided with an individual die plate of the rupture cut type. The die plate is preferably formed in such a manner that the transverse cut line between adjacent carton blank images is located generally centrally of the die plate. Register means is provided adjacent the center of the die plate or segment to assist in registering the die to the printed image. Also, preferably, the segments have a circumferential length such that small gaps are formed in the nature of ten thousandths to thirty thousandths of an inch between the ends of the segments. These gaps enable the segments to be slightly adjusted circumferentially relative to the arbor for purposes of effecting proper cutting of the material and also for adjusting one part of the die plate relative to another part of the die plate.
Also, since the segments are removable, different thickness segments can be positioned on the arbors. This adjustment can readily occur for purposes of print length variation. The use of segments with individual die plates also minimizes the problem of inaccuracies which are created in the prior art due to the fact that a single die plate is secured substantially around a cylinder. Further, simplification in making the die plates is achieved since the step and repeat operation or the equivalent is simplified. Also, damage to one die plate requires replacement of only that small die plate as opposed to the prior art where the entire large die plate had to be replaced.
Further in accordance with the present invention, the gaps which are formed between the segments on one cylinder are preferably offset from the gaps which are formed between the segments on the other cylinder when the gaps arrive at the cutting nip. It has been discovered that the rupture cut principle is such that even though such gaps do occur, the cut line will propagate across the gap and an effective cut will occur even though the gaps are present. The offsetting of the gaps at the nip minimizes any nicking or the like which might occur and assists in the propagation of the cut line across the gaps.
Further in accordance with the present invention, the segments are provided with suitable pins for assisting in the removal of broke from the carton blanks after the carton blanks are cut from the material. Specifically, the segments on one of the arbors is provided with a plurality of pins and a cam bar which actuates the pins. The cam bar is operated by a cam which moves the bar axially of the cylinder and which bar on movement actuates the pins. The pins engage the broke and assist in the removal of the broke. Since the pins, bar and segment are unitary, quick easy mounting on the machine is enabled.
Further in accordance with the present invention, the arbors are adjustable toward and away from each other for purposes of adjusting the radial gap between the arbors. This adjustment is a running adjustment and can be effected during rotation of the arbors even though the arbors are gear driven. This running adjustment is provided by a unique structural arrangement of the gear drive to the arbors which enables the running adjustment to occur while the arbors are being gear driven.